Bright pixels appear on my model in material preview with Cycles on Blender 2.82
So I opened your file on my machine and have to inform you that the glitches only occur on your end.

The doughnut looks just fine in my Viewport:



And renders beautifully (this render was done with only 8 samples in about 7 seconds):



Since you are using a laptop I suspect the switch between IntelHD-Graphics and your dedicated chip my be the cause of this problem. Since I'm not a Windows user I can only give you limited advice on this issue:


Make sure all your hardware drivers are up to date.
Start Blender with your GTX enabled (right-click on the application, then choose something like "run with NVIDIA")
If that doesn't solve your issues and you're positive that neither your OS nor your hardware are at fault here, try filing a Blender bug-report.